Process for the removal of natural oils, wax, and spray residues from fruits



Patented Oct. 1932 UNITED STATES PATENT OFFICE.

REGINALD H. ROBINSON, or CORVALLIS, onneon, DEDICATED, BY MESNE Assmn- MENTS,

IPROCESS FOR THE REMOVAL OF NATURAL OILS, WAX, AND SPRAY BESIDUEB FBOI TO THE IPEOPLE OF THE UNITED STATES OF AMERICA FRUITS No Drawing;

(GRANTED UNDER. THE ACT This application is .made under the act of March 3, 1883, chapter 143 (22 Stat. 625) as amended April 30, 1928 R. 6103) and in accordance therewith applicant states that the invention described herein, if patented, may be manufactured and used by or for the Government for governmental purposes without the payment to him of any royalty thereon.

This invention relates to a method for the removal of part or all of the natural oil or waxy coating that forms on the surface of apples and pears as they mature and to the removal of residual oil that has accumulated 5 on the fruit from repeated spraying of oil emulsions during the growing season, which wax and oil interferes with and prevents the removal of spray residue by recognized fruit washing processes.

During the past few yearsthe fruit industry has been required by health authorities to remove toxic spray residues-that is, lead arsenate and other arsenicals-from fruits and vegetables. This has been accomplished by washing the fruit in suitable washing apparatuses or machines with a solvent that dissolves the residue. A. water solution of hydrochloric acid has proved to be the most effective solvent and most of the spray covered fruits can be cleaned with this chemical within the required tolerance, providing no influencing factors retard the solvent action of the hydrochloric acid. It has been found, however, that when wax forms on the surface of the fruit as it matures or when oil sprays have been used throughout the growing season that the particles of lead arsenate are coated with the wax or the oil which prevents efiective cleaning by the hydrochloric acid process. If, however, a suitable solvent or combination of solvents that will dissolve the wax or the oil is added to the hydrochloric acid, enough of the wax or oil is dissolved to permit the acid to act upon and dissolve the lead arsenate. Laboratory experiments confirmed by packing house tests have shown that certain organic compounds or mixtures of compounds are effective for dissolving the natural wax and residual oils left on fruit.

The solvents for the natural oil or wax of Application filed February 19, 1930. Serial 1%. 429,805.

or macs a, 1888, as Ammonia APRIL 30, 192a; 3700. e. 757

apples and pears and for residual oils from o1]v sprays are alcohols such as methyl, ethyl,

glycerineand certain of the higher alcohols, acetone, benzol and its higher homologues, various hydrocarbons such as benzine, gasoline and others of different hydrocarbon series, carbon tetrachloride, commercial lacquer solvents, sulfonated oils, chloroform, amyl acetate, carbon disulphide, ether, alkalies, soa s,-and various organic acids such asv ince some of these solvents are 1moleic. miscible with a water solution of hydrochloric acid that is used in the washing process, it is necessary to emulsify them or to'make combinations of two or more of the above specified solvents by which an emulsion is formed which can be dispersed through the hydrochloric acid solution. The process of the invention consists in adding any of the solvents or combination of solvents for wax or oil to the hydrochloric acid solution in the tank of the fruit washing machine. When the machine is operated the mixture of hydrochloric acid and organic solvents is sprayed through jets or brought into contact with the fruit by other means employed in the various commercial washing machines and the organic solvent dissolves enough of the wax or the oil from the fruit to permit the hydrochloric acid to act upon and dissolve effectively the lead arsenate particles. The amount of organic solvent necessary to dissolve the wax or oil on the fruit depends upon the amount of the wax that has formed on the fruit or oil that has been applied as an oil spray. Fruit heavily coated with wax or oil requires more of the organic solvent than fruit less heavily coated. The amount of organic solvent necessary, therefore, depends upon the amount of Wax or oil on the fruit, the temperature of the solution of hydrochloric acid in the washing machine when the fruit is being washed, the amount of agitation given or the force applied through the jets, and the amount and nature of the arsenical residue present.

While I have stated that the solventused for removing the wax or oil is added to the dilute hydrochloric acid in the fruit washing. machine, it is to be understood that it may be used separately or with any other solvent that has been found eifective for dissolving the spray residues.

I claim:

5 A process for the removal of natural oils, wax and spray residues from fresh fruits comprising the application to the fresh fruits of a solution of liquid petroleum hydrocarbons, hydrochloric acid and water, followed by washing with'water to remove the cleaning solution and then drying the fruit.

REGINALD H. ROBINSON. 

